Stitch forming drive mechanism



E W. BIALY March 29, 1966 STITCH FORMING DRIVE MECHANISM 3 Sheets-Sheet 1 Filed Jan. 28, 1964 INVENTOR.

EdWOfd W. B q|y BY ATTORNEY WITNESS March 29, 1966 w, B|ALY 3,242,891

STITCH FORMING DRIVE MECHANISM Filed Jan. 28, 1964 3 Sheets-Sheet 2 Fig. 2

INVENTOR. Edward W. Biclly WITNESS M I ATTORNEY E. W. BIALY March 29, 1966 STITCH FORMING DRIVE MECHANISM 3 Sheets-Sheet 3 Filed Jan. 28, 1964 Fig. 4

Fig. 5

INVENTOR. Edward W. Bialy TTORNEY WITNESEM United States Patent 3,242,891 STITCH FORMING DRIVE MECHANHSM Edward W. Bialy, Hillside, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Jan. 28, 1964, Ser. No. 340,725 6 Claims. (Cl. 112226) This invention relates to a drive mechanism for the stitch forming inst-rurrnentalities of a sewing machine.

The various portions of a drive member for the stitch forming instrumentalities of a sewing machine are subject to widely differing conditions during sewing machine operation, which dictates correspondingly wide differences in the steps and'processes necessary for manufacture, in the choice of materials, and in the degree of accuracy, quality and finish which are requisite to satisfactory operation.

It is, therefore, an object of the present invention to provide an arrangement in the drive mechanism for the stitch forming instrumentalities of a sewing machine whereby various parts may be manufactured separately, each under the conditions best suited thereto, and then subassembled in a novel and effective fashion.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings in which:

FIG. 1 is a side elevational view of a sewing machine emrbodying'the present invention in which portions of the machine frame are broken away to show interior details;

FIG. 2 is a bottom plan view of the sewing machine with the bottom cover removed;

FIG. 3 is a cross sectional view taken substantially along the line 33 in FIG. 1;

FIG. 4 is an enlarged cross sectional view taken substantially along the line 44 in FIG. 1; and

FIG. 5 is an enlarged cross sectional view taken substantially along the line 5-5 in FIG. 2.

With reference to the drawings, the invention is incorporated in a sewing machine having a frame including a hollow work supporting bed with a hollow standard 11 rising from one end thereof and terminating at its upper end in a hollow bracket arm 12 that extends laterally over the work supporting bed 10.

A main shaft 13 is rotatably mounted within the hollow bracket arm 12 and entends longitudinally therethrongh. An endwise reciprocable thread-carrying needle 14 is operatively connected to the main shaft 13 by conventional means which are well known. The main shaft 13 has a crank 15 formed in an intermediate portion thereof with a cam surface thereon. in the hollow standard 11 by means of pin-tle screws 17. At its upper end the pitman 16 is slotted to provide a cam follower 18 in engagement with the cam surface of the crank 15, and to adjust the clearance between the cam follower 18 and the cam surface of the crank 15 the pitman is fitted with a screw 19.

A stitch forming mechanism drive bar 20 is pivotally connected to the bottom of the pitman 16 by means of a pivot screw 21. The drive bar 20 has an inverted U- shaped cross section with a plurality of cross braces 22. The drive bar 20 is of such design that it can readily be die cast.

A rack element 23 and a cam member 24 are connected to the free end of the drive bar 20 by means of screws 25. It is within the scope of the invention to use other fastening means in lieu of the screws 25. The rack 23 has a substantially rectangular cross section and is conveniently seated within a portion of the inverted U-shaped cross section of the drive bar 20 and its teeth are in engagement with the teeth of a drive pinion or gear 26 which is con- A pitman 16 is pivotally mounted 3,242,891 Patented Mar. 29, 1966 "ice nectcd by means of a setscrew 27 to the bottom of a vertical aXis loop-taker shaft 28 to which a conventional form of loop-taker 29 is affixed.

A bracket or rack guide 30 is formed with a transverse bore which accommodates a headed adjustable eccentric member 31 by which the guide rack 30 is pivotally secured to the bottom of the work supporting bed 10 and maintained in abutment with the rack 23.

The adjustable eccentric member 31 includes an eccentric portion 3-2 arranged within the transverse bore of the rack guide member 30, from which eccentric portion extends a stud 33 having a neck portion 34. A setscrew 35 bearing against the neck portion 34 of the adjustable eccentric member 31 holds the rack guide 30 against the bottom of the work supporting bed 10 and an extension 36 of the rack guide 30 embraces a corner of the rectangular cross section of the rack 23 thereby to support the rack 23 in engagement with the teeth of the gear 26. By turning the adjustable eccentric member 31, the clearance between the teeth of the rack 23 and the gear 26 may be adjusted, and the pivotal support for the rack guide 30 provided by the eccentric member 31 permits the rack guide to oscillate thus to accommodate the angular component of motion of the rack 23 and drive bar 20 during operation of the sewing machines.

A feed lift cam follower 37 in engagement with the cam 24 secured on the top of the drive bar 20 is connected to a work feeding mechanism including a feed bar 38 which in turn carries a feed dog 39. A tension spring 40 is stretched between a screw 41 on the feed'bar 38, and a bracket 42 connected to the bottom of the work supporting bed 10 by means of a screw 43. The tension spring 40 holds the cam follower 37 in engagement against the cam 24 connected to the top of the drive bar 20. Other biasing means could be used in lieu of the tension spring 40.

In operation, as the main shaft 13 rotates in the direction of the arrow 44, for example, the needle 14 is reciprocated and the cam surface of the crank 15 causes the pitman 16 to oscillate. The oscillatory motion of the pitman 16 is translated into a combination of angular and reciprocatory motions of the stitch forming mechanism drive bar 20. The reciprocatory component of motion of the drive bar 20, through the rack 23 and gear 26, causes the loop taker 29 to oscillate in timed relation to the needle 14.

As the drive bar 26 reciprocates, the cam 24 imparts lift motion to the Work feeding mechanism including the feed dog 39 through the cam follower 37 and the feed bar 38. Feed advance motion is imparted to the feed dog 39 by means of a feed advance rock shaft 45 and necessary connections (not shown) to the main drive shaft 13 so that the work feeding mechanism will be actuated in timed relation with the needle and loop taker.

Thus, a new and useful stitch forming drive mechanism has been provided for sewing machines. The stitch forming drive bar 20 can be inexpensively formed out of cast metal while the more critical rack 23 andcam 24 are easily machined or produced by investment casting, sintering, etc. The unique inverted U-shaped cross section ofthe drive bar 20 can not only be easily cast but provides a means for seating the rack 23 against lateral movement and without adding to the vertical clearance required in the hollow work supporting bed 10. The adjustable eccentric 31 of the rack guide 30 provides a means for accommodating the motion of the rack and drive bar as well as for adjusting the clearance between the teeth of the rack 23 and the gear 26 as the parts Wear. When a part has ultimately worn out, it can be replaced at much less cost than would be required to replace the entire mechanism. In addition, the drive bar 20 performs the added 3 function of imparting lift mot-ion to the feed dog 39 through the cam 24.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention.

What is claimed is:

1. In a sewing machine having a frame, stitch forming instrumentalities carried in said frame including a needle end-wise reciprocable in said frame, a loop taker shaft journaled in said frame, a circularly moving loop taker and a drive pinion fast on said loop taker shaft, a main drive member carried in said frame, means operatively connecting said main drive member to said endwise reciprocable needle, and means for imparting circular movement to said loop taker in timed relation with said reciprocable needle comprising a drive bar formed with a U- shaped cross section carried in said frame, a rack member formed with gear teeth and formed with a substantially rectangular cross section sized to seat snugly within said drive bar U-shaped cross section, fastening means for securing said rack member to one extremity of said drive bar within said U-shaped cross section, guide means for maintaining said rack member gear teeth in mesh with said loop taker drive pinion, and means driven by said main drive member and operatively connected to the opposite extremity of said drive bar for imparting an endwise reciprocatory component of motion to said drive bar.

2. In a sewing machine having a frame, stitch forming instrumentalities carried in said frame including a needle endwise reciprocable in said frame, a loop taker shaft journaled in said frame, a circularly moving loop taker and a drive pinion fast on said loop taker shaft, work feeding mechanism, a main drive shaft journaled in said frame, means operatively connecting said main drive shaft to said endwise reciprocable needle, and means for imparting operative movements to said loop taker and to said work feeding mechanism in timed relation with said reciprocable needle comprising a drive bar carried in said frame, a rack member formed with gear teeth, fastening means for securing said rack member to one extremity of said drive bar, a feed actuating cam member secured to said drive bar by said rack member fastening means in operative engagement with said work feeding mechanism, guide means for maintaining said rack member gear teeth in meshwith saidv loop taker drive pinion, and means driven by said main drive shaft and operatively connected to the opposite extremity of said drive bar for imparting an end-Wise reciprocatory component of motion to said drive bar.

3. In a sewing machine as set forth in claim 2 in which said rack member is formed with a substantially rectangular cross section sized to seat snugly within said drive bar Ushaped cross section and in which said feed actuating cam is secured by said fastening means at the opposite side of said drive bar from said rack member.

4. The sewing machine of claim 1 in which said guide means for maintaining said rack member gear teeth in mesh with said loop taker drive pin-ion includes a bracket slidably engaging said rack member at the side directly opposite from the rack member gear teeth, an extension on said bracket overlapping a portion of the rack member to support the rack member, pivot means pivotally connecting the bracket to said sewing machine frame, eccentric means on said pivot means, and means for adjusting said eccentric means to. shift said bracket laterally thereby adjusting the clearance between the rack member gear teeth and the loop taker drive pinion.

5. In a sewing machine having a frame, stitch forming instrumentalities carried in said frame including a needle endwise reciprocable in said frame, aloop taker shaft journaled in said frame, a circularly moving loop taker and a drive pinion fast on said loop taker shaft, a work feeding mechanism, a main drive shaft journaled in said frame, means operatively connecting said main drive shaft to said endwise reciproca'ble needle, and means for imparting operative movements to said loop taker and to said work feeding mechanism in timed relation with said reci-procable needle comprising a drive barcarried in said frame, a rack member formed with gear teeth, fastening means for securing said rack member to one extremity 01 said drive bar, a feed actuating cam member secured to said drive bar in operative engagement with said work feeding mechanism, guide means for maintaining said rack member gear teeth in mesh with said loop taker drive pinion. and means driven by said main drive shaft and operatively connected to the opposite extremity of said drive bar for imparting an endwise reciprocatory component of motion to said drive bar.

6. In a sewing machine having a frame, stitch forming instrnmentalities carried in said frame including a needle endwise reciprocable in said frame, a loop taker shaft journaled in said frame, a circularly moving loop taker and a drive pinion fast on said loop taker shaft, a work feeding mechanism, a main drive shaft journaled in saidframe, means operatively connecting said main drive shaft to said endwise reciprocable needle, and means for imparting operative movements to said loop taker and to said work feeding mechanism in timed relation with said reciproca ble needle comprising a drive bar carried in said frame, a rack member formed with gear teeth, fastening means for securing said rack member to one extremity of said drive bar, a feed actuating cam member secured to said drive bar in operative engagement with said work feeding mechanism, a bracket slidably engaging said rack member at the side directly opposite from the rack member gear teeth, an extension on said bracket overlapping a portion of the rack member to support the rack member, pivot means pivotally connecting the bracket to said sewing machine frame, eccentric means on said pivot means, means for adjusting said eccentric means to shift said ibracket laterally thereby adjusting the clearance between the rack member gear teeth and the loop taker drive pinion, and means driven by said main drive shaft and operatively connected to the opposite extremity of said drive bar for imparting an. endwise reciprocatory component of motion to said drive bar.

References Cited by the Examiner UNITED STATES PATENTS 326, 8 21 9/ 18 Whitehill 112-220 X 780,028 1/ 1905 .Finkle l12'184 961,135 6/1910 Jacob 112-184 1,622,780 3 1927 Goodline 74422 2,414,227 1/1947 Goforth 112-184 FOREIGN PATENTS 106,5 78 6/ 1927 Austria.

FRANK J. COHEN, Primary Examiner.

JORDAN FRANKLIN, R. V. SLOAN,

Assistant Examiners. 

1. IN A SEWING MACHINE HAVING A FRAME, STITCH FORMING INSTRUMENTALITIES CARRIED IN SAID FRAME INCLUDING A NEEDLE END-WISE RECIPROCABLE IN SAID FRAME, A LOOP TAKER SHAFT JOURNALED IN SAID FRAME, A CIRCULARLY MOVING LOOP TAKER AND A DRIVE PINION FAST ON SAID LOOP TAKER SHAFT, A MAIN DRIVE MEMBER CARRIED IN SAID FRAME, MEANS OPERATIVELY CONNECTING SAID MAIN DRIVE MEMBER TO SAID ENDWISE RECIPROCABLE NEEDLE, AND MEANS FOR IMPARTING CIRCULAR MOVEMENT TO SAID LOOP TAKER IN TIMED RELATION WITH SAID RECIPROCABLE NEEDLE COMPRISING A DRIVE BAR FORMED WITH A USHAPED CROSS SECTION CARRIED IN SAID FRAME, A RACK MEMBER FORMED WITH GEAR TEETH AND FORMED WITH A SUBSTANTIALLY RECTANGULAR CROSS SECTION SIZED TO SEAT SNUGLY WITHIN SAID DRIVE BAR U-SHAPED CROSS SECTION, FASTENING MEANS FOR SECURING SAID RACK MEMBER TO ONE EXTREMITY OF SAID DRIVE BAR WITHIN SAID U-SHAPED CROSS SECTION, GUIDE MEANS FOR MAINTAINING SAID RACK MEMBER GEAR TEETH IN MESH WITH SAID LOOP TAKER DRIVE PINION, AND MEANS DRIVEN BY SAID MAIN DRIVE MEMBER AND OPERATIVELY CONNECTED TO THE OPPOSITE EXTREMITY OF SAID DRIVE BAR FOR IMPARTING AN ENDWISE RECIPROCATORY COMPONENT OF MOTION TO SAID DRIVE BAR. 